Who is the Shortland Street serial killer?

There's a serial killer on the loose in our favourite soap. We investigate the motives for Shortland Street's latest cull

It's been a big year for Shortland Street. In May, our national soap celebrated its 15-year anniversary at a boozy, VIP event - Robyn Malcolm's presence proved there really is life after the Street; Craig Parker's proved there is reincarnation.

Two months later at the New Zealand TV Screen Awards, Anna Jullienne was named best supporting actor for her role as lesbian nurse Maia. The hospital got a makeover, the staff got new mauve uniforms and ex-All Black Buck Shelford was written into an episode.

But good things don't last - at least, not in soap land.

Fans were left reeling when Claire (Emily Robins), the former hellraiser-turned-goody-good receptionist, was found dead in a skip.

Then Meg (Emily Mowbray) was killed, sending fans into a whodunnit spin, Kieran and Mark named as likely suspects. "The murderer could be anyone," gushed a blogger on throng.co.nz. "Even a woman."

But it was Jay's shock death on Monday that sent fans straight to the anti-depressants. "She was a sexy lezzy with the golden pouring hand and the best hair I've ever seen," stammered a distressed Alice, after discovering her friend's body.

So it seems Shortland Street has a serial killer on its hands. But with crime shows a dime a dozen, and TV killers not exactly a dying breed, why bring a whodunnit to the sanitised halls of our PC, family-friendly, 7pm soap?

A good cast spring-clean and a shot at bigger ratings is the obvious answer. More than 17 million tuned in to see Coronation Street's Richard Hillman admit that he was a killer after several popular murder episodes in 2003.

But it's also for the challenge, says producer Jason Daniel, who points out that soaps rarely tackle plots of this nature. While there was no secret about Evil Dom's murderous intentions in 2003, no one knows who the killer is this time - and we're unlikely to find out soon.

"To do a really good whodunnit means telling a really good mystery story across several weeks or months. Normally serials don't do that because it's hard to maintain mystery over a long period.

"You have to keep all of those clues and the factual evidence of the story consistent."

Daniel won't say how many core cast members will be knocked off but Jay won't be the last. Nor will he say exactly when the killer will be revealed but it is likely the police won't solve the case until just before Christmas. That suggests the story will snowball in time for a rip-roaring cliffhanger, or at least open up new storyline possibilities for the new year.

"Each incident is different from the one before so that it's not just a question of people dying relentlessly. They all add something to the story and provide us with a few more clues and a few more red herrings."

Naturally, there is some expert subterfuge to maintain secrecy. Only Daniel and a "tiny few" key writers know who the killer is. Even the killer doesn't yet know who the killer is. Daniel also sent out fake storylines to safeguard against potential leaks. The cast will shoot three versions of the big revelation, meaning three people will get to play killer but only one will go to air, a technique similar to that used to film the Sex & the City finale.

"There are about three or four actors who all think they're the killer," says Daniel. "There's much debate going on, a few bets as well."

Selecting the victims is a case of who will be surprising, says Daniel. It is also a matter of deciding who has done their time on the show. Mark has been set up as a main suspect and sent packing this week, which will come as a relief to those waiting for a resolution of the Mark-Tania-Maia triangle.

"I don't think there was any future in their marriage given the degree of deception there," says Daniel. "We have to make way for new characters, and as much as we want to keep all of the characters we like, if we do that the show starts to stagnate and we can't really keep things moving on. And you can't really change the dynamic of the cast every now and then which is what we need to do to keep it fresh."

Such cast culls have historically, been a sensitive issue. During a revamp in 2001 when the fictional clinic came under Government ownership, 14 characters went on their way, some of the dumped actors complaining of having their "guts ripped out".

A year after the clinic CEO Huia Samuels announced she was about to embark on serious cutbacks, she got a taste of her own medicine when she was obliterated by a car bomb.

Nicola Kawana, who played Huia, was reported to have responded angrily to her character's demise, interrupting the filming schedule by not showing up to work, and refusing to talk to the press.

But if there's any ill feeling among the axed cast this time, it's not rearing its head with quite the same vigour. Perhaps it's because there is no one actor - not even Michael Galvin, who plays the soap's only original cast member Chris Warner - with a contract longer than 12 months.

"Nicola's situation was extreme because she has a family and she was worried about supporting them and all that sort of stuff," says Tim Foley, whose character Mark, a suspect, leaves this week. It's early days for Foley but he plans to return to the theatre.

"I personally think that if you enter into this industry, nothing's permanent and most actors go long periods of time without any employment. So while it's very scary and hard to be facing that situation again, it's what I signed up for. I've had three years so I'm very lucky."

Jaime Passier-Armstrong, who played Jay until her grisly demise, feels the same way. Originally she wanted to leave in March when her contract was up. Daniel asked her to hang in there for another five months for the sake of the story.

"I was only supposed to be on the show for three months originally. I never expected to stay on there for three years," she laughs.

"Shortland Street has been an extraordinary journey but it consumes your life, basically. I'm an extremely family-oriented person and I haven't been able to have much time in the last three years for myself or my family."

For now, she has no plans other than to keep riding her horse, spending time with loved ones and doing things she has put off because of the show. "I'm normally a very driven person but I'm so happy to have this time to myself. I'm really happy to take each day as it comes."

Which is all one can hope for characters who are about to die. All bets are on.